Save Gas With The Unchecked Keyword

[code423n4]

Handle

ye0lde

Vulnerability details

Impact

Redundant arithmetic underflow/overflow checks can be avoided when an underflow/overflow cannot happen.

Proof of Concept

The "unchecked" keyword can be applied here since there is an "if" statement to ensure the arithmetic operations would not cause an integer underflow or overflow.
https://github.com/code-423n4/2022-01-timeswap/blob/bf50d2a8bb93a5571f35f96bd74af54d9c92a210/Timeswap/Timeswap-V1-Convenience/contracts/libraries/Mint.sol#L278

Change the code at 278 to:

        unchecked { 
		 if (maxCollateral > dueOut.collateral) ETH.transfer(payable(msg.sender), maxCollateral - dueOut.collateral);
	} 

Similar changes can be made here:
https://github.com/code-423n4/2022-01-timeswap/blob/bf50d2a8bb93a5571f35f96bd74af54d9c92a210/Timeswap/Timeswap-V1-Convenience/contracts/libraries/Mint.sol#L396
https://github.com/code-423n4/2022-01-timeswap/blob/bf50d2a8bb93a5571f35f96bd74af54d9c92a210/Timeswap/Timeswap-V1-Convenience/contracts/libraries/Mint.sol#L436
https://github.com/code-423n4/2022-01-timeswap/blob/bf50d2a8bb93a5571f35f96bd74af54d9c92a210/Timeswap/Timeswap-V1-Convenience/contracts/libraries/Mint.sol#L557

https://github.com/code-423n4/2022-01-timeswap/blob/bf50d2a8bb93a5571f35f96bd74af54d9c92a210/Timeswap/Timeswap-V1-Convenience/contracts/libraries/Pay.sol#L62

Tools Used

Visual Studio Code, Remix

Recommended Mitigation Steps

Add the "unchecked" keyword as shown above.

[amateur-dev]

Similar issue highlighted over here #156 ; hence closing this.